JP2017176378A - sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sewing machine which can avoid inconvenience caused by dynamic resistance of a needle thread becoming excessive, and which can execute smooth sewing.SOLUTION: A sewing machine includes: a balance moving vertically being interlocked with the rotation of a main shaft; and a needle bar capable of mounting a sewing needle which passes a needle thread extended through the balance. The sewing machine also includes: a first thread guide part 42 having a first guide passage 42b for guiding the needle thread extended through the balance to the needle bar; and a second thread guide part 10 provided at the needle bar, and having a second guide passage 10b for guiding the needle thread guided by the first thread guide part 42 to the sewing needle. The width d of the second guide passage 10b in the direction along the main shaft is made to be equal to or greater than the width D of the first guide passage 42b in the direction along the main shaft.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a sewing machine, and more particularly to a sewing machine having a yarn guide portion on a yarn path of an upper yarn.

  The sewing machine passes the sewing needle from the upper surface side of the sewing product and feeds the upper thread to the lower side of the sewing product, and also hooks the upper thread with the hook that holds the lower thread by driving the hook mechanism and entangles it with the lower thread. The sewing product is sewn with.

  The sewing machine has the upper thread in the following order: thread spool, upstream thread guide, secondary thread tensioner, main thread tensioner, thread hook, middle flow right thread guide, balance, middle flow left thread guide, downstream thread guide, sewing needle Is guided as a yarn path.

  When the sewing machine is sewing the sewing product by the vertical movement of the sewing needle, the balance also moves up and down in conjunction with the vertical movement of the sewing needle. At this time, the cycle of the vertical movement of the balance is different from the cycle of the vertical movement of the sewing needle. Therefore, the upper thread is in a tension state when the balance is at the top dead center (uppermost position) and is in a relaxed state when the balance is at the bottom dead center (lowermost position).

  In this way, during the sewing to the sewing product by the sewing machine, the upper thread repeats between the tensioned state and the slack relaxed state. The upper thread is consumed by advancing the thread path from the thread piece toward the sewing needle as the balance and the sewing needle move up and down.

  In Patent Document 1, in the process in which the upper thread advances in the yarn path, tension and relaxation of the upper thread are allowed particularly between the thread guide and the needle bar thread guide installed between the balance and the sewing needle. . At this time, in Patent Document 1, the needle bar thread guide is fixed to a needle bar metal that holds the upper end of the sewing needle and holds the needle bar that moves up and down integrally with the sewing needle.

  Specifically, as shown in FIG. 11, the downstream thread guide 100 includes an annular fixed portion 101 for fixing to the needle bar metal 110 and a substantially S-shape in plan view formed continuously with the fixed portion 101. And a guide portion 103 having a ring shape in plan view formed continuously with the elastic portion 102. The elastic portion 102 is elastically deformed in the front-rear direction according to a change in tension generated when the upper thread T passed through the guide portion 103 changes between a tension state and a relaxed state interlocked with the vertical movement of the sewing needle. Further, with a focus on stabilization of sewing, the diameter of the guide portion 103 is relatively narrow in order to prevent the upper thread T from being violated.

JP 2008-167913 A

  However, in the sewing machine of Patent Document 1, the width (corresponding to the diameter) of the guide portion 103 of the needle bar thread guide 100 is narrow, and the dynamic resistance to the upper thread T when the upper thread T passes through the guide portion 103 is small. It gets too big.

  Therefore, the resistance when the hook pulls the upper thread T is increased, the amount and timing of the upper thread T being pulled becomes unstable, or the upper thread T loosened around the needle bar thread guide 100 is caused by the elastic portion 102. The problem of getting entangled or going around the back of the needle bar occurs. Therefore, the hook cannot smoothly pull the upper thread T, and there is a problem that the thread tightening is deteriorated. Even if the elastic portion 102 is provided to alleviate the dynamic resistance, the needle bar thread guide 100 becomes complicated and large in size, and there is a problem that the design of the entire sewing machine needs to be changed, such as securing an arrangement space.

  An object of the present invention is to provide a sewing machine that can avoid inconveniences due to excessive dynamic resistance of an upper thread and can perform smooth sewing.

  The sewing machine according to the first invention of the present application is a sewing machine including a balance that moves up and down in conjunction with rotation of a main shaft and a needle bar that can be fitted with a sewing needle that passes an upper thread that is passed over the balance. A first thread guide portion having a first guide passage for guiding the upper thread to the needle bar, and a second guide provided in the needle bar for guiding the upper thread guided by the first thread guide section to the sewing needle. A second yarn guide portion having a passage, wherein a width of the second guide passage in a direction along the main shaft is equal to or greater than a width of the first guide passage in a direction along the main shaft. To do.

  The sewing machine of the first invention of the present application is provided with a first yarn guide portion and a second yarn guide portion. The first yarn guide portion includes a first guide passage through which the upper yarn passed over the balance is passed. The second yarn guide portion includes a second guide passage through which the upper yarn guided by the first yarn guide portion is passed. The width of the second guide passage is at least the width of the first guide passage. The passage resistance of the upper thread in the second guide passage is at least equivalent to the passage resistance in the first guide passage. The second thread guide portion can allow the movement of the upper thread guided from the balance to the sewing needle and sewn into the sewing product in the same manner as the first thread guide portion.

  The sewing machine can reduce the dynamic resistance of the upper thread along the path from the balance to the sewing needle in the process of changing from the state where the upper thread is slack to the state where the tension is applied. Specifically, the sewing machine can prevent the upper thread from escaping out of the second guide path and drooping without sufficiently guiding the upper thread from the balance to the sewing needle, and the resistance when the shuttle pulls the upper thread increases. Can be prevented. The sewing machine can also prevent the upper threads from getting entangled and wound when the hook pulls the thread with the upper thread hanging down. Therefore, the sewing machine can stabilize the formation of the seam in the sewing product.

  The sewing machine according to a second aspect of the present invention is the sewing machine according to the first aspect, wherein the second thread guide portion includes an arc portion extending in an arc shape along an outer peripheral portion of the needle bar, and an end portion of the arc portion. A first straight portion extending linearly on one side; a first bent portion that folds back to the opposite side of the needle bar on the opposite side of the arc portion of the end of the first straight portion; and the first bent portion A second linear portion facing in parallel with the first linear portion and extending linearly from the end of the first linear portion, and bent toward the needle bar at the end of the second linear portion, and the first linear portion And a second bent portion having a closed loop shape together with the first bent portion and the second straight line portion, and the second guide passage is formed inside the closed loop shape.

  In the sewing machine according to the second aspect of the present invention, the second yarn guide portion includes a first straight portion and a second straight portion that face each other, a first bent portion, and a second bent portion. The closed loop shape forming the second guide passage includes a first straight portion and a second straight portion. The second guide passage is long along the straight direction of the first straight portion and the second straight portion. The sewing machine improves the degree of freedom of the upper thread when passing through the second guide passage, and can reliably reduce the dynamic resistance of the upper thread.

  The sewing machine according to a third aspect of the present invention is the sewing machine according to the second aspect, wherein at least a part of the second bent portion is positioned above the arc portion and the arc portion is seen in a plan view. It is characterized by overlapping.

  In the sewing machine according to the third aspect of the present invention, at least a part of the second bent portion is positioned above the arc portion and overlaps the arc portion in plan view. Therefore, the upper thread passing through the second guide passage is unlikely to come off from the second guide passage. The sewing machine can reliably guide the upper thread in the second guide passage and reduce the dynamic resistance of the upper thread.

  The sewing machine according to a fourth aspect of the present invention is characterized in that, in the sewing machines according to the first to third aspects of the present invention, the position of the second thread guide portion can be adjusted along the circumferential direction of the needle bar.

  In the sewing machine of the fourth invention of the present application, the position of the second thread guide portion can be adjusted along the circumferential direction of the needle bar. The sewing machine can move the second guide passage toward the pedestal portion by sliding the second thread guide portion in the circumferential direction, or conversely move the second guide passage toward the side away from the pedestal portion. . The sewing machine can adjust the dynamic resistance of the upper thread.

  According to the present invention, it is possible to avoid inconvenience due to excessive dynamic resistance of the upper thread, and to perform smooth sewing.

It is a front view of a sewing machine. FIG. 3 is a front view of the vicinity of the tip of the arm portion of the sewing machine. (A) is a bottom view of the midstream left thread guide, and (B) is a plan view of the downstream thread guide. It is a front view of the vicinity of the arm portion tip of the sewing machine equipped with the downstream yarn guide of the comparative example. It is a top view of the downstream yarn guide of a comparative example. It is explanatory drawing of the balance fall state in the sewing machine of a comparative example. It is explanatory drawing of the balance raising state in the sewing machine of a comparative example. It is explanatory drawing of the sewing machine of a balance fall state. It is explanatory drawing which shows the sewing result at the time of sewing two fabrics using the downstream thread guide of a comparative example. It is a top view of the downstream yarn guide of a modification. It is a top view of the conventional downstream yarn guide.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the upper side, lower side, left side, right side, front side, and rear side of FIG. 1 are respectively the upper side, lower side, left side, right side, front side, and rear side of the sewing machine 1.

  In FIG. 1, a sewing machine 1 includes a work table 2 including a bed (not shown), a pedestal 3, and an arm 4. The bed portion supports the work table 2 in an embedded state so as to be flush with the upper surface (work surface) of the work table 2. The work table 2 includes a needle plate 21 on the upper surface of the left end portion. The bed portion is provided with a shuttle mechanism, a thread trimming mechanism, and the like. However, since various mechanisms relating to the sewing are known, detailed description thereof is omitted here. The pedestal 3 extends upward from the right side of the work table 2.

  The arm portion 4 extends leftward from the upper end side of the pedestal column portion 3 and integrally has a tip portion 5 at the left end portion. An operation unit (not shown) and a yarn supply source (not shown) such as a thread spool stand are provided on the upper surface of the central portion of the arm unit 4 as necessary. Inside the arm portion 4, a main shaft (not shown by reference sign P in FIG. 1) rotated by a sewing machine motor (not shown) is arranged along the longitudinal direction (left-right direction). The tip portion 5 is a portion whose lower end protrudes downward from the arm portion 4.

  The tip 5 is an upstream yarn guide 6, a sub-tension device 20, a main tension device 30, and a midstream yarn guide 7 in order from the upstream side as a yarn path of the upper yarn T drawn from an upper yarn supply source (not shown) such as a thread spool. The upper thread guide member 40, the balance 8, the downstream thread guide 10, and the needle hole 11a of the sewing needle 11 are provided. In addition, the upstream, middle stream, and downstream in each yarn guide are for convenience of description, and are not limited to one, and may include a plurality of yarn guides. The tip 5 feeds the work cloth N in cooperation with a feed mechanism (not shown) when sewing the work cloth N set on the upper surface of the needle plate 21, and the work cloth N when sewing by the vertical movement of the sewing needle 11. The presser foot unit 50 that suppresses the impact (up and down movement) generated on the foot is provided. Since the feed mechanism is provided in the bed portion and is a known configuration, detailed description thereof is omitted.

  The upstream yarn guide 6 is made of a rod-like metal or the like that stands up from the upper surface of the distal end portion 5, and has two upper and lower guide holes 6a and 6b. After the upper thread T pulled out from the thread spool passes through the upper guide hole 6a from the rear (back side) to the front (front side), wraps around again, and passes through the lower guide hole 6a from the rear to the front. , It is bridged to the sub-tone device 20.

  The secondary tension device 20 adjusts the tension of the upper thread T on the upstream side. The sub-tensioning device 20 functions as a sub-tension applying device that suppresses unexpected threading of the upper yarn T from the yarn supply source and applies a lower tension to the upper yarn T than the main tensioning device 30. In addition, since the concrete structure and effect | action of the subtone apparatus 20 use the well-known thing, the detailed description is abbreviate | omitted here.

  The main tension device 30 adjusts the tension of the upper thread T on the downstream side. The main tension device 30 is larger than the sub-tone device 20 on the upper thread T, and functions as an assertion force applying apparatus that applies tension to the upper thread T during sewing. In addition, since the concrete structure and effect | action of the main tone apparatus 30 use the well-known thing, the detailed description is abbreviate | omitted here.

  The midstream yarn guide 7 guides the upper yarn T that has passed through the main tension device 30 by turning it back toward the upper balance 8.

  The upper thread guide member 40 includes a middle flow right thread guide 41 and a middle flow left thread guide 42 that are disposed on the substantially same plane so as to be opposed to the left and right. The middle-stream right thread guide 41 guides the upper thread T turned back by the middle-stream thread guide 7 toward the balance 8. The midstream left thread guide 42 guides the upper thread T that has been passed over the balance 8 toward the downstream thread guide 10. As shown in FIG. 3 (A), the middle left thread guide 42 has a base part 42a for screw fixing to the front wall surface of the front end part 5, and one end of the base part 42a bent forward in a loop shape so that the upper thread T A first thread guide portion 42c for guiding. A space that the first yarn guide portion 42c surrounds with the base portion 42a is a first guide passage 42b.

  As shown in FIG. 3B, the downstream thread guide 10 has a substantially bar shape, and an annular arc part 10a for fixing to the needle bar metal 12 and an upper thread T guided by the first thread guide part 42c are sewn as sewing needles. 11 has a second yarn guide portion 10c having a second guide passage 10b for guiding to 11, and an annular portion 10d formed continuously with the second yarn guide portion 10c. The arc portion 10 a has substantially the same shape as the outer diameter of the needle bar metal 12 and is fixed to the needle bar metal 12. The needle bar metal 12 has a groove recessed in the radial direction at the lower end. The downstream yarn guide 10 can be fixed by fitting the arc portion 10a into the groove portion.

  The second yarn guide portion 10c includes an arc portion 10a, a first straight portion 10e, a first bent portion 10f, and a second straight portion 10g. The arc portion 10 a extends in an arc shape along the outer peripheral portion of the needle bar 9. One end portion of the first straight portion 10e is continuous with the end portion of the arc portion 10a, and extends linearly from the one end portion to one side. One end portion of the first bent portion 10f is continuous with the other end portion of the first linear portion 10e, and is folded back from the one end portion to the side opposite to the needle bar 9. The second linear portion 10g has one end continuous to the other end of the first bent portion 10f, faces the first linear portion 10e in parallel from the one end, and extends linearly. The annular portion (second bent portion) 10d bends toward the needle bar 9 at the other end of the second straight portion 10g, and is closed loop with the first straight portion 10e, the first bent portion 10f, and the second straight portion 10g. Make. The inside of the closed loop shape is the second guide passage 10b.

  The second guide passage 10b is formed in a long hole shape that is long in the left-right direction along the main axis P by continuously forming the second yarn guide portion 10c so as to be folded back from the arc portion 10a. The second guide passage 10b has a width d along the left-right direction equal to or greater than a width D of the first guide passage 42b in the left-right direction. The center in the left-right direction of the width d of the second guide passage 10b (near the position of the upper thread T shown in FIG. 3B) and the left-right center of the width D of the first guide path 42b (upper thread shown in FIG. 3A). (Near the position of T) is substantially the same center position in the vertical direction.

  The balance 8 is located between the middle flow right thread guide 41 and the middle flow left thread guide 42 on the yarn path, and lifts the upper thread T by moving up and down in conjunction with the rotation of the main shaft P. The balance 8 moves up and down in conjunction with the up and down movement of the needle bar body 13 of the needle bar 9 and the sewing needle 11. As shown in FIG. 1, the balance 8 is usually covered with a balance cover 8 </ b> A so that an operator does not accidentally touch it during sewing. In FIG. 2 and the like, the balance cover 8A is not shown for convenience of explanation.

  The needle bar 9 has a cylindrical needle bar metal 12 provided at the lower end of the tip 5 and a needle bar main body 13 held by the needle bar metal 12 so as to be movable up and down.

  The needle bar main body 13 has a substantially cylindrical shape extending in the vertical direction inside the tip portion 5, and reciprocates up and down (on a straight line) via a crank mechanism (not shown) by the clockwise rotation of the main shaft P in the left side view. To do. The needle bar main body 13 is provided at its lower end so that the sewing needle 11 can be replaced. The needle bar body 13 has a thread guide hole 13a formed at the lower end. The upper thread T passes from the outer side to the inner side through the thread guide hole 13 a, and guides the upper thread T to the needle hole 11 a of the sewing needle 11. The thread guide hole 13a is formed in a substantially perfect circle shape (substantially vertically long oval shape in a front view) with respect to the cylindrical needle bar body 13. The center of the thread guide hole 13a is substantially the same in the vertical direction as the center of the width d of the second guide passage 10b in the left-right direction (near the position of the upper thread T shown in FIG. 3B). The diameter of the yarn guide hole 13a is narrower than the width d of the second guide passage 10b and the width D of the first guide passage 42b.

  As shown in FIG. 1, the presser foot unit 50 includes a presser bar 51, a presser foot 52, a presser bar holder 53, an adjustment holder 54, and an adjustment screw 55. The presser bar 51 has a substantially cylindrical shape extending in the up-down direction inside the distal end portion 5. The presser foot 52 is attached to the lower end portion of the presser bar 51 so as to be detachable (replaceable). The presser bar holder 53 is provided in the lower part of the tip 5 and has a cylindrical shape that holds the presser bar 51 so as to be movable up and down. The adjustment holder 54 supports the upper end of the presser bar 51 so as to be movable up and down inside the distal end portion 5. The adjustment holder 54 protrudes upward from the upper surface of the distal end portion 5. The adjustment holder 54 has a male screw formed on the outer periphery. The adjustment holder 54 adjusts the position in the vertical direction by changing the amount screwed into the tip 5, and adjusts the pressing force of the work cloth N by the presser foot 52. The nut 55 is screwed into the male screw of the adjustment holder 54 on the upper surface of the distal end portion 5 to position the adjustment holder 54 in the vertical position. Since the presser foot unit 50 can be of a known configuration, detailed description thereof is omitted here. Further, the presser foot unit 50 is shown only in FIG. 1 for convenience of explanation.

  In such a basic configuration of the sewing machine 1, the sewing machine 1 according to the present embodiment can be equipped with a balance 8 that moves up and down in conjunction with the rotation of the main shaft P and a sewing needle 11 that passes an upper thread T that spans the balance 8. In the sewing machine 1 including the needle bar 9, a first thread guide portion 42c having a first guide passage 42b for guiding the upper thread T spanned over the balance 8 to the needle bar 9 and the needle bar 9 are provided with the first thread guide portion 42c. A second yarn guide portion 10c having a second guide passage 10b for guiding the upper thread T guided by the yarn guide portion 42c to the sewing needle 11. The width d of the second guide passage 10b in the direction along the main axis P is provided. The width is equal to or greater than the width D of the first guide passage 42b in the direction along the main axis P.

  Thus, in the present embodiment, the first yarn guide portion 42c and the second yarn guide portion 10c are provided. The first yarn guide portion 42 c includes a first guide passage 42 b through which the upper yarn T spanned over the balance 8 is passed. The second yarn guide portion 10c includes a second guide passage 10b through which the upper yarn T guided by the first yarn guide portion 42c passes. The width d of the second guide passage 10b is at least equal to or greater than the width D of the first guide passage 42b. Therefore, the passage resistance of the upper thread T in the second guide passage 10b is at least equal to the passage resistance in the first guide passage 42b. The second thread guide portion 10c can allow the movement of the upper thread T guided from the balance 8 to the sewing needle 11 and sewn into the sewing product, in the same manner as the first thread guide portion 42c.

  The sewing machine 1 can reduce the dynamic resistance of the upper thread T in the path from the balance 8 to the sewing needle 11 in the process of changing from the state in which the upper thread T is slack to the state in which the tension is applied. Specifically, the sewing machine 1 can prevent the upper thread T from coming out of the second guide passage 10b and hanging down without sufficiently guiding the upper thread T from the balance 8 to the sewing needle 11, and the shuttle can It is possible to prevent an increase in resistance when pulling T. The sewing machine 1 can also prevent the upper threads T from being entangled or wound when the hook pulls the threads with the upper threads T hanging down. Therefore, the sewing machine 1 can stabilize the formation of the seam in the sewn product.

  The second yarn guide portion 10c includes a first straight portion 10e and a second straight portion 10g, a first bent portion 10f, and a second bent portion that face each other. The closed loop shape forming the second guide passage 10b includes a first straight portion 10e and a second straight portion 10g. The second guide passage 10b is long along the linear direction of the first straight part 10e and the second straight part 10g. In the sewing machine 1, the degree of freedom of the upper thread T when passing through the second guide passage 10b is improved, and the dynamic resistance of the upper thread T can be reliably reduced.

  Since the degree of freedom of the upper thread T is improved, the slack of the upper thread T can be reduced even when the balance 8 is lowered, and then the upper thread T passes through the straight line even when the balance 8 is raised again. become.

  Therefore, the middle flow left thread guide 42 and the downstream thread guide 10 disposed between the balance 8 and the needle bar body 13 that move up and down at different timings are generated as the balance 8 and the needle bar body 13 move up and down, respectively. It has a function of absorbing the tension change of the yarn T. Here, the change in tension of the upper thread T that occurs when changing between the tension state and the relaxed state interlocked with the vertical movement of the sewing needle 11 is provided in the downstream thread guide 10 disposed immediately above the needle bar body 13. Absorption is performed by the second guide passage 10b having a width d. The change in tension of the upper thread T that occurs when the balance 8 changes between a tension state and a relaxed state that are linked to the vertical movement of the balance 8 is a first guide having a width D provided in the midstream left thread guide 42 directly below the balance 8. Absorb in the passage 42b.

  In addition, since the width d in the direction along the main axis P of the second guide passage 10b is equal to or larger than the width D in the direction along the main axis P of the first guide passage 42b, a configuration for absorbing extra shock is provided. Therefore, it is not necessary to consider the design change of the entire sewing machine 1 caused by the above, and since the width d of the first guide passage 42b is wide, the dynamic resistance can be reduced and the upper thread entanglement with the downstream thread guide 10 is generated. Can be difficult.

  Specifically, as shown in FIGS. 4 and 5, comparison is made in the case where the downstream yarn guide 60 is arranged instead of the downstream yarn guide 10. The downstream thread guide 60 is substantially rod-shaped, and a second fixing section 60a for guiding the upper thread T guided by the first thread guide section 42c to the sewing needle 11 and the annular fixing section 60a for fixing the needle bar 9 to the needle bar metal 12 is provided. It has the 2nd thread guide part 60c which has the guide channel 60b, and the cyclic | annular part 60d formed continuously from the 2nd thread guide part 60c. The width d 'in the direction along the main axis P of the second guide passage 60b is narrower than the width d in the direction along the main axis P of the second guide passage 10b.

  In this comparative example, as shown in FIG. 6, when the balance 8 is lowered and the upper thread T is in a slack state, the upper thread T tends to flow to the right side of the tip 5 due to the slack of the upper thread T. . At this time, since the width d 'is narrower than the width d, the slack upper thread T is caught by the downstream thread guide 60, and a loop is formed so as to spread over the entire upper, lower, left, and right sides of the downstream thread guide 60.

  Therefore, as shown in FIG. 7, when the balance 8 is raised and the upper thread T is going to be in a tension state, the upper thread T tends to be entangled with the downstream thread guide 60. When the upper thread T is entangled with the downstream thread guide 60, the upper thread T enters between the fixed part 60a, the second thread guide part 60c, and the needle bar 9. Therefore, the dynamic resistance of the upper thread T increases along the path from the balance 8 to the sewing needle 11 in the process of changing from the state in which the upper thread T is slack to the state in which the tension is applied.

  On the other hand, in the downstream yarn guide 10, as shown in FIG. 8, when the balance 8 is lowered and the upper yarn T is in a loosened state, the width d is wider than the width d ′, so The yarn T is slackened only below the downstream yarn guide 10.

  Therefore, as shown in FIG. 2, when the balance 8 rises and the upper thread T is going to be in a tension state, the upper thread T can be returned to the tension state without being entangled with the downstream thread guide 10.

  The downstream yarn guide 10 is merely fixed to the groove portion of the needle bar metal 12 of the needle bar 9 by the arc portion 10a, and is not fixed by a screw or the like. Therefore, for example, as shown in FIG. 3 (B) by an arcuate double-ended arrow, if the arc portion 10a is slid counterclockwise or clockwise in plan view along the circumferential direction of the needle bar metal 12, the second guide portion is provided. The direction of 10c can be adjusted.

  Therefore, if the downstream yarn guide 10 is slid counterclockwise in plan view in FIG. 3B, the second guide passage 10b can be moved to the right side of the sewing machine 1, and conversely, the downstream yarn guide 10 is moved to FIG. The second guide passage 10b can be brought to the left side of the sewing machine 1 by sliding it clockwise in plan view. Therefore, the yarn path around the downstream yarn guide 10 can be finely adjusted left and right, and the dynamic resistance of the upper yarn T can be further finely adjusted.

  In addition, since the dynamic resistance can be reduced, for example, not only sewing on the thick work cloth N as in the prior art described above, but also sewing of a “very thin fabric” such as a female blouse, for example. Correspondence becomes possible.

  Referring to FIG. 9, a sewing result when two fabrics are sewn using the downstream thread guide 60 is shown. In FIG. 9, two fabrics are designated as an upper fabric N1 and a lower fabric N2, and the upper fabric N1 is laid over the lower fabric N2 and sewn.

  FIG. 9A shows a case where sewing is performed by applying a relatively strong tension when the upper fabric N1 and the lower fabric N2 are very thin fabrics. At this time, when the upper fabric N1 was viewed from the top, there was a problem that so-called puckering that would cause wrinkles around the seams was likely to occur.

  On the other hand, in order to avoid the occurrence of puckering, a weak tension (for example, 5 grams, 10 grams) must be used. If the tension is weakened mainly focusing on the occurrence of puckering, the downstream yarn guide 60 is caused by the dynamic resistance to the upper yarn T, and even if the occurrence of puckering can be avoided, the “thread tightening” will occur. Deteriorate. When the thread tightening is bad, as shown in FIG. 9B, when the upper fabric N1 is viewed from above, it appears that the stitches are formed without any problem. However, as shown in FIG. 9C, when the end portion of the upper fabric N1 is rolled up and spread in a double-page spread, a gap S is formed between the upper fabric N1 and the lower fabric N2.

  On the other hand, in the downstream yarn guide 10, since the problem of dynamic resistance to the upper yarn T has been solved, even if the tension is set to be weak, “thread tightening” is unlikely to deteriorate. That is, it is difficult to form a gap S between the upper fabric N1 and the lower fabric N2. Therefore, the sewing machine 1 can be sewn at a low tension without deteriorating the quality of the sewing product.

  The present invention can be variously modified without departing from the spirit of the present invention.

  For example, in the downstream yarn guide 10, at least a part of the annular portion (second bent portion) 10d may be located above the arc portion 10a and overlap the arc portion 10a in plan view. As shown in FIG. 10, the downstream yarn guide 110 includes an arc portion 10a, a second yarn guide portion 10c, and an annular portion 110d. The annular portion 110d bends toward the needle bar 9 at the other end of the second linear portion 10g, is positioned above the arc portion 10a, and overlaps the arc portion 10a in plan view. In this case, the downstream yarn guide 110 can prevent the upper yarn T passing through the second guide passage 10b from coming off between the arc portion 10a and the annular portion 110d. Even in this case, the annular portion 110d bends toward the needle bar 9 at the other end of the second straight portion 10g, and forms a closed loop shape together with the first straight portion 10e, the first bent portion 10f, and the second straight portion 10g. .

  The downstream thread guide 10 can slide the arc portion 10a counterclockwise or clockwise in plan view along the circumferential direction of the needle bar metal 12, but may be fixed to the needle bar metal 12 with a screw or the like, for example.

  The width d along the left-right direction of the second guide passage 10b may be equal to or greater than the width D of the first guide passage 42b in the left-right direction. For example, the first straight part 10e and the second straight part 10g may be curved in directions away from each other. The first bent portion 10f may be bent at one end and the other end at right angles, and between the one end and the other end may be linear.

DESCRIPTION OF SYMBOLS 1 Sewing machine 8 Balance 9 Needle bar 42 Middle flow left thread guide 42b 1st guide path 42c 1st thread guide part 10 Downstream thread guide 42b 2nd guide path 42c 2nd thread guide part

Claims (4)

A balance that moves up and down in conjunction with the rotation of the spindle,
In a sewing machine comprising a needle bar to which a sewing needle for passing an upper thread passed over the balance can be attached,
A first thread guide portion having a first guide passage for guiding the upper thread that is stretched over the balance to the needle bar;
A second thread guide portion provided on the needle bar and having a second guide passage for guiding the upper thread guided by the first thread guide portion to the sewing needle;
The sewing machine characterized in that the width of the second guide passage in the direction along the main axis is equal to or greater than the width of the first guide passage in the direction along the main axis. The second thread guide portion is
An arc portion extending in an arc shape along the outer periphery of the needle bar;
A first linear portion extending linearly from one end to the other end of the arc portion;
A first bent portion that folds back to the opposite side to the needle bar on the side opposite to the arc portion of the end of the first straight portion;
A second straight line portion that faces the first straight line portion in parallel from the end of the first bent portion and extends linearly;
A second bent portion that bends toward the needle bar at the end of the second straight portion, and that forms a closed loop with the first straight portion, the first bent portion, and the second straight portion;
The sewing machine according to claim 1, wherein the second guide passage is formed inside the closed loop shape. The second thread guide portion is
The sewing machine according to claim 2, wherein at least a part of the second bent portion is located above the arc portion and overlaps the arc portion in plan view. The second thread guide portion is
The sewing machine according to any one of claims 1 to 3, wherein the position can be adjusted along a circumferential direction of the needle bar.

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